Modular belts are highly valued for their flexibility, and many facilities, especially in the food industry, use them as radius belts on conveyors with curves. Here are some of the things to keep in mind when using modular belts as radius belts.
Modular radius belts can run along the entire conveyor, curves included
Standard modular belts consist of modules held together by rods inserted through circular holes along the sides of the modules. With radius belts, the holes on one side of the modules are oblong, enabling the rod to move and the belt to “collapse” and fold inwards as it enters a curve on the conveyor. This means that a singular modular belt can be used for the entire conveyor, along straight sections as well as in the curves.
Fabric belts can also be used as radius belts, but they do not have this kind of flexibility, so separate conveyors and drives/motors are needed to run along straight sections and around the curves. This results in a greater number of transitional phases throughout the conveying process, which may negatively affect both the products and the applications. Using a fabric belt can also be a more expensive solution, as it requires more motors and conveyor components.
Calculating the collapse factor, and why it matters
A radius belt must be able to collapse and adjust to a new, stable mode when entering a curve. The inner side of the belt – facing the curve – will collapse, while the outer side of the belt will keep its pitch. In order for this to work, you need to know the so-called collapse factor of your belt. This is the factor by which you must multiply the width of your belt to find the correct inner radius of the curve.
A common standard is 2.2 – meaning that in such cases, 2.2 x the width of the belt = the inner radius of the curve. However the value 2.2 is matching only with a certain belt width. Below this width the collapse factor is usually getting smaller, above bigger. While other belt manufacturer neglect this given geometric fact Habasit allows proper conveyor designs by showing this correlation in tables on the datasheet.
This is often incorrectly thought of as a minimum radius, interpreted that any belt with a radius larger than this supposed minimum can be used. However, such a belt will only become more unstable and noisy, and also wear out faster. Ideally, the inner radius of the conveyor should match the radius of the belt that has been calculated with the relevant collapse factor.
Take load distribution into account to minimize radius belt wear
Habasit radius belts can take high loads, because the edge section is designed to handle high forces in a curve. However the force a radius belt can handle in straight section is higher, since the load is evenly distributed across the belt. Therefore the general recommendation is to have the curve close to the entrance (lower force in the radius section) of the conveyor and not at the end.
The reaction force from the pulling force through the curve is generating a significant amount of pressure against the wear strip. If the combination of speed and pressure gets too high, the plastic runs the risk of melting. Using SeleCalc, our Habasit engineering program, you can calculate the load strain on your radius belt. You can also find out how long your belts need to be, based on the number of curves along the conveyor. In case of critical applications (high speed and force) feel free to consult a Habasit specialist.
Habasit modular belts are easy to repair
Using a modular belt as a radius belt makes it simple to repair. A broken or worn out module is easily replaced by a new one, and the belt can be up and running again within minutes. A damaged fabric belt, by comparison, might have to be replaced altogether, which is both costly and time-consuming. If broken, the rods holding the modules together can easily be replaced using a Habasit rod puller or in case of the patent protected Smartfit rod retaining a screw driver
Modular radius belts are flush grids by definition. As modular radius belts need to be able to collapse, they are in fact flush grids. As such, air and liquids are able to pass through them. But please note: if the radius belt needs to be completely flat – also known as a flat top – you should use a fabric radius belt without holes or other irregularities on its surface.
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